Hitherto, in photographing of a subject with a large difference in luminance between a bright part and a dark part in an imaging apparatus such as a camera, photographing with a changed exposure condition is performed plural times, and obtained images are combined, thereby performing the photographing with an expanded dynamic range of the imaging apparatus. For example, such a system is proposed that a histogram is generated from an image signal obtained by first photographing and it is determined with the histogram whether or not second photographing is performed and, in the second photographing, an exposure condition is obtained from the histogram acquired by the first photographing (see, for example, Patent Literature 1).